1. Field of the Invention
The present invention relates generally to regulating flow of refrigerant in air conditioning units and more specifically to regulating flow of refrigerant in systems providing stored thermal energy for use during peak electrical demand.
2. Description of the Background
With the increasing demands on peak demand power consumption, ice storage has been utilized to shift air conditioning power loads to off-peak times and rates. A need exists not only for load shifting from peak to off-peak periods, but also for increases in unit capacity and efficiency. Current air conditioning units having energy storage systems have had limited success due to several deficiencies including reliance on water chillers that are practical only in large commercial buildings and difficulty in achieving high efficiency. In order to commercialize advantages of thermal energy storage in large and small commercial buildings, the thermal energy storage system must have minimal manufacturing costs, maintain maximum efficiency under varying operating conditions, emanate reliability and simplicity in the refrigerant management design, and maintain flexibility in multiple refrigeration or air conditioning applications.
Systems for providing stored thermal energy have been previously contemplated in U.S. Pat. No. 4,735,064 and U.S. Pat. No. 4,916,916 both issued to Harry Fischer, U.S. Pat. No. 5,647,225 issued to Fischer et al, and U.S. patent application Ser. No. 10/967,114 filed Oct. 15, 2004, by Narayanamurthy et al. All of these patents utilize ice storage to shift air conditioning loads from on-peak to off-peak electric rates to provide economic justification and are hereby incorporated by reference for all they teach and disclose.